Assessment of topical versus oral ivermectin as a treatment for head lice

Antiparasitic activity of ivermectin: Four decades of research into a "wonder drug"

Parasitic diseases still pose a serious threat to human and animal health, particularly for millions of people and their livelihoods in low-income countries. Therefore, research into the development of effective antiparasitic drugs remains a priority. Ivermectin, a sixteen-membered macrocyclic lactone, exhibits a broad spectrum of antiparasitic activities, which, combined with its low toxicity, has allowed the drug to be widely used in the treatment of parasitic diseases affecting humans and animals. In addition to its licensed use against river blindness and strongyloidiasis in humans, and against roundworm and arthropod infestations in animals, ivermectin is also used "off-label" to treat many other worm-related parasitic diseases, particularly in domestic animals. In addition, several experimental studies indicate that ivermectin displays also potent activity against viruses, bacteria, protozoans, trematodes, and insects. This review article summarizes the last 40 years of research on the antiparasitic effects of ivermectin, and the use of the drug in the treatment of parasitic diseases in humans and animals.

Broadening the range of use cases for ivermectin - a review of the evidence

Ivermectin is a broad-spectrum antiparasitic agent that interferes with glutamate-gated chloride channels found in invertebrates but not in vertebrate species. Mass drug administration (MDA) with ivermectin-based regimes has been a mainstay of elimination efforts targeting onchocerciasis and lymphatic filariasis for more than 3 decades. More recently, interest in the use of ivermectin to control other neglected tropical diseases (NTDs) such as soil-transmitted helminths and scabies has grown. Interest has been further stimulated by the fact that ivermectin displays endectocidal efficacy against various Anopheles species capable of transmitting malaria. Therefore there is growing interest in using ivermectin MDA as a tool that might aid in the control of both malaria and several NTDs. In this review we outline the evidence base to date on these emerging indications for ivermectin MDA with reference to clinical and public health data and discuss the rationale for evaluating the range of impacts of a malaria ivermectin MDA on other NTDs.

Clinical interventions for tungiasis (sand flea disease): a systematic review

Tungiasis (sand flea disease) is an epidermal parasitic skin disease occurring in resource-limited communities. There is no standard treatment for tungiasis, and available treatment options are scarce. To our knowledge, this is the first systematic review aimed to assess randomised controlled trials (RCTs) investigating interventions for tungiasis. We systematically searched databases including MEDLINE (EBSCOhost), CENTRAL, CINAHL, PubMed, Web of Science, SciELO, LILACS and Embase (Scopus) for RCTs in any language, from inception of the databases until June 12, 2021. RCTs exploring preventive and therapeutic interventions for tungiasis were eligible. We used the revised Cochrane Collaboration's risk of bias tool to assess the risk of bias and Jadad scale to quantify the methodological quality of the RCTs. Of the 1839 identified records, only eight RCTs involving 808 participants were included, and several methodological deficiencies were identified in most of the trials. Trial interventions included: oral drugs niridazole and ivermectin and topical interventions of ivermectin lotion, metrifonate lotion, thiabendazole lotion, thiabendazole ointment, dimeticones (NYDA), and a neem seed and coconut oils-based mixture for treatment and coconut oil-based lotion (Zanzarin) for prevention. The coconut oil-based lotion for prevention and dimeticones for treatment of tungiasis have displayed the most promise. Most of the RCTs included in this study had low methodological quality. There is a clear unmet need for high-quality RCTs examining safe and effective prevention and treatment alternatives of tungiasis in endemic settings.

The molecular targets of ivermectin and lotilaner in the human louse Pediculus humanus humanus: New prospects for the treatment of pediculosis

Control of infestation by cosmopolitan lice (Pediculus humanus) is increasingly difficult due to the transmission of parasites resistant to pediculicides. However, since the targets for pediculicides have no been identified in human lice so far, their mechanisms of action remain largely unknown. The macrocyclic lactone ivermectin is active against a broad range of insects including human lice. Isoxazolines are a new chemical class exhibiting a strong insecticidal potential. They preferentially act on the γ-aminobutyric acid (GABA) receptor made of the resistant to dieldrin (RDL) subunit and, to a lesser extent on glutamate-gated chloride channels (GluCls) in some species. Here, we addressed the pediculicidal potential of isoxazolines and deciphered the molecular targets of ivermectin and the ectoparasiticide lotilaner in the human body louse species Pediculus humanus humanus. Using toxicity bioassays, we showed that fipronil, ivermectin and lotilaner are efficient pediculicides on adult lice. The RDL (Phh-RDL) and GluCl (Phh-GluCl) subunits were cloned and characterized by two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes. Phh-RDL and Phh-GluCl formed functional homomeric receptors respectively gated by GABA and L-glutamate with EC₅₀ values of 16.0 μM and 9.3 μM. Importantly, ivermectin displayed a super agonist action on Phh-GluCl, whereas Phh-RDL receptors were weakly affected. Reversally, lotilaner strongly inhibited the GABA-evoked currents in Phh-RDL with an IC₅₀ value of 40.7 nM, whereas it had no effect on Phh-GluCl. We report here for the first time the insecticidal activity of isoxazolines on human ectoparasites and reveal the mode of action of ivermectin and lotilaner on GluCl and RDL channels from human lice. These results emphasize an expected extension of the use of the isoxazoline drug class as new pediculicidal agents to tackle resistant-louse infestations in humans.

Human cosmopolitan lice are responsible for pediculosis, which represent a significant public health concern. Resistant lice against insecticides and lack of safety of the treatments for human and environment is a growing issue worldwide. Here we investigated the efficacy on lice of the classical macrocyclic lactone drug, ivermectin, and of the isoxazoline drug, lotilaner. This study was done to decipher their mode of action at the molecular and functional levels in order to propose new strategies to control lice infestation. Our bioassay results indicate that ivermectin and lotilaner were potent at killing human adult lice, with lotilaner showing a higher efficacy than ivermectin. Furthermore, we identified and pharmacologically characterized the first glutamate- and GABA-gated chloride channels ever described in human lice yet. Mechanistically, our molecular biology and electrophysiology findings demonstrate that ivermectin acted preferentially at glutamate channels, while lotilaner specifically targeted GABA channels. These results provide new insights in the understanding of the insecticide mode of action and highlight the potential of isoxazolines as a new alternative for the treatment of human lice.

[Parasitoses in childhood]

Parasitoses are a frequent occurrence in pediatric consultations in both hospitals and private practices. Responsible for this are parasites that permanently infest human skin, such as Sarcoptes scabiei hominis and Pediculus humanus capitis (persistent parasites) as well as those that only attack the skin for feeding, such as Pulex irritans, Cimex lectularius und Neotrombicula autumnalis (transient parasites). The main symptom of parasitoses is pruritus, which is caused by a delayed allergic reaction to proteins in the saliva of the parasites. In some parasitoses, such as scabies, the pruritus is typical, occurs particularly at night and is associated with a considerable impairment in the quality of life due to the resulting lack of sleep, whereas the pruritus is often absent in the case of pediculosis capitis. In this article persistent and transient parasitoses are characterized based on the patient history, morphology and symptoms.

Pediculosis capitis in Abidjan, Côte d'Ivoire: Epidemiological profile and associated risk factors

Pediculosis capitis (PC) is a parasitic infestation, common in children's communities caused by Pediculus humanus capitis. Various factors including infestation-related stigma, treatment cost and health risks make this infestation deserves special attention. This study aims to determine epidemiological profile of pediculosis capitis twenty years after the last study in Abidjan, Côte d’Ivoire.

An epidemiological cross-sectional survey was carried out from April to June 2018 across 40 public primary schools in the ten districts of Abidjan. Data from schoolchildren and parents and/or guardians were collected using a pretested questionnaire after agreement and signature of the informed consent form. Head lice were identified visually with a magnifying glass, and then collected using fine combs and hairbrushes. The positive diagnosis was made by the detection of living lice in the hair.

Of the 4, 805 included participants, 28 (0.58%) were hosting living lice in hair. Analysis of associated factors showed that gender related-status was associated with PC. In this case, girls were more affected than boys (p=0.018). Plateau, Treichville and Port Bouët municipalities were the most affected (p=0.018). The length hair was associated with the occurrence of PC (p<0,001). Schoolchildren from families with low monthly income was most infected by PC (p=0.023). Some parameters such as promiscuity and collective use of washing facilities and bedding, were not found to be associated to head lice infestation.

This study shows a drastic decrease of PC prevalence in Abidjan corresponding to 97%. This could be due to the improvement in the quality of life and education of the population of Abidjan. The establishment of hygiene committees and the teaching of basic hygiene practices from the first school years have contributed to these achievements. Maintaining these measures will contribute to the sustainable elimination of CP among children in Abidjan.

Prevalence and Alternative Treatment of Head-Lice Infestation in Rural Thailand: A Community-Based Study

Head-lice infestation, pediculosis capitis, remains a public-health burden in many countries. The widely used first-line pediculicides and alternative treatments are often too costly for use in poor socio-economic settings. Ivermectin has been considered an alternate treatment for field practice. This study was composed of 2 parts, a cross-sectional survey and an intervention study. The main objectives were to determine the prevalence and potential factors associated with head-lice infestation, and to evaluate the effectiveness and safety of oral ivermectin administration. A community-based cross-sectional survey was conducted among 890 villagers in rural areas along Thai-Myanmar border. Females with infestations were eligible for the intervention study, and 181 participated in the intervention study. A post-treatment survey was conducted to assess acceptance of ivermectin as a treatment choice. Data analysis used descriptive statistics and a generalized-estimation-equation model adjusted for cluster effect. The study revealed the prevalence of head-lice infestation was 50% among females and only 3% among males. Age stratification showed a high prevalence among females aged <20 years, and among 50% of female school-children. The prevalence was persistent among those with a history of infestation. The major risk factors were residing in a setting with other infected cases, and sharing a hair comb. The study also confirmed that ivermectin was safe and effective for field-based practice. It was considered a preferable treatment option. In conclusion, behavior-change communication should be implemented to reduce the observed high prevalence of headlice infestation. Ivermectin may be an alternative choice for head-lice treatment, especially in remote areas.

Effective treatments for head lice

Head lice is a parasitic infestation common in children. Proper management is essential to treat lice in a safe, convenient, cost-effective, and efficacious manner. School lice policies are often antiquated and can stigmatize the child and family. Evidence-based care guidelines may significantly help families minimize the stress of lice.

Impact of ivermectin administered for scabies treatment on the prevalence of head lice in Atoifi, Solomon Islands

Background

Scabies and head lice are ubiquitous ectoparasitic infestations that are common across the Pacific Islands. Ivermectin is an effective treatment for both conditions, although the doses used vary. At a community level, mass drug administration (MDA) with ivermectin is an effective strategy to decrease prevalence of scabies. To what extent MDA with ivermectin will also reduce prevalence of head lice is unknown.

Methodology

Head lice prevalence was assessed before and after MDA with oral ivermectin (at a dose of 200 micrograms per kilogram of body weight) administered on day 1 and day 8. The primary outcome was the change in prevalence of head louse infestation at two weeks compared to baseline. Longer term efficacy was assessed three months after MDA.

Results

118 participants were enrolled. Baseline prevalence of active head louse infestation was 25.4% (95% CI 18.4–34.0). At two-week follow-up, prevalence was 2.5% (95% CI 0.9–7.2), a relative reduction of 89.1% (95% CI 72.7–91.4%, p<0.001). At three-month follow-up, prevalence was 7.5% (95% CI 2.7–12.3), a relative reduction of 70.6% (95% CI 72.7%-91.4%, p <0.001). Head louse infestation was associated with younger age (age ≤10 years: prevalence 46.7%; adjusted odds ratio compared to adults of 7.2, 95%CI 2.0–25.9) and with having at least one other member of the household with active head louse infestation (adjusted odds ratio 4.3, 95%CI 1.7–11.1).

Conclusions

Head louse infestation is common in the Solomon Islands. This proof of principle study shows that oral ivermectin at a dose of 200 micrograms per kilogram can reduce the burden of active head louse infestation, offering an additional collateral benefit of MDA with ivermectin for scabies control.

Trial registration

ClinicalTrials.gov NCT03236168.

Head lice and scabies are both caused by ectoparasites and lead to itchy skin conditions that are associated with secondary bacterial infections and social stigma. Both are common in developing countries. In the Solomon Islands, mass treatment of communities using ivermectin (at dose of 200 micrograms per kilogram) has been shown to be an effective strategy in reducing scabies prevalence. This study shows that the same dose of ivermectin and the same regime of mass drug administration is also effective at reducing the burden of head louse infestation, offering an additional benefit to community wide treatment.

Oral ivermectin for the treatment of head lice infestation

PURPOSE

Published literature describing the use of oral ivermectin for the treatment of head lice infestation is reviewed.

SUMMARY

In the United States and globally, head lice infestation, or pediculosis capitis, remains a public health issue with both social and medical implications. Treatment with oral or topical medications is typically required for head lice eradication. Resistance to traditional topical therapies for head lice infestation is increasing, creating a need for consideration of additional treatment options. A growing body of data describing the potential role of oral ivermectin for the treatment or prevention of head lice infestation is available. A literature search identified 5 clinical trials that evaluated safety and/or effectiveness outcomes of oral ivermectin use as an alternative to malathion, other topical prescription medications, and traditional, nonprescription remedies; those studies were conducted in various parts of the world (e.g., Australia, Brazil, Mexico, Egypt) and likely involved varying types and degrees of lice resistance. Clinical research findings to date, while not consistently robust, suggest that oral ivermectin is comparable or superior in effectiveness to other topical treatment options for head lice infestation while being well tolerated and favorably perceived by patients and caretakers.

CONCLUSION

Oral ivermectin is an option for the treatment of head lice infestation, especially in individuals who have experienced a treatment failure. Published evidence from clinical trials indicates that oral ivermectin is as effective as currently available topical treatments.

Common Child and Adolescent Cutaneous Infestations and Fungal Infections

Cutaneous infections and infestations are common among children and adolescents. Ectoparasitic infestations affect individuals across the globe. Head lice, body lice, scabies, and infestations with bed bugs are seen in individuals who reside in both resource poor areas and in developed countries. Superficial cutaneous and mucosal candida infections occur throughout the life cycle. Dermatophyte infections of keratin-containing skin and skin structures result in tinea capitis (scalp), tinea corporis (body), tinea pedis (foot), and tinea unguium (nails). Less frequent endemic fungal infections such as blastomycosis, coccidiodomycosis, and histoplasmosis may present with skin findings. This article will describe the epidemiology and transmission of these conditions as well as their clinical manifestations. The approach to diagnosis will be addressed as well as primary prevention and current therapies.